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Man can't hear in a crowded restaurant.

Sometimes when a person has a difficult time hearing, someone close to them insultingly suggests they have “selective hearing”. When your mother used to accuse you of having “selective hearing,” she was suggesting that you paid attention to the part about chocolate cake for dessert and (perhaps intentionally) ignored the part about cleaning your room.

But it turns out that selective hearing is quite the skill, an impressive linguistic accomplishment conducted by cooperation between your brain and ears.

The Difficulty Of Trying to Hear in a Crowd

Maybe you’ve experienced this scenario before: you’re feeling tired from a long day at work but your friends all really would like to go out for dinner and drinks. And naturally, they want to go to the loudest restaurant (because it’s popular and the deep-fried cauliflower is delicious). And you strain and struggle to understand the conversation for over an hour and a half.

But it’s difficult, and it’s taxing. And it’s a sign of hearing loss.

Maybe, you rationalize, the restaurant was just too noisy. But no one else appeared to be having difficulties. You seemed like the only one having trouble. So you begin to wonder: what is it about the packed room, the cacophony of voices all battling to be heard, that causes hearing impaired ears to struggle? It seems as if hearing well in a crowd is the first thing to go, but what’s the reason? The solution, according to scientists, is selective hearing.

Selective Hearing – How Does it Work?

The phrase “selective hearing” is a process that doesn’t even happen in the ears and is formally called “hierarchical encoding”. This process nearly entirely takes place in your brain. At least, that’s as reported by a new study done by a team from Columbia University.

Scientists have known for quite a while that human ears essentially work as a funnel: they gather all the signals and then send the raw information to your brain. That’s where the real work happens, particularly the auditory cortex. Vibrations caused by moving air are interpreted by this portion of the brain into recognizable sound information.

Because of comprehensive research with MRI and CT scans, scientists have recognized for years that the auditory cortex plays a substantial role in hearing, but they were stumped with regards to what those processes really look like. Scientists were able, by making use of novel research techniques on individuals with epilepsy, to get a better picture of how the auditory cortex discerns voices in a crowd.

The Hierarchy of Hearing

And the facts they found out follows: most of the work done by the auditory cortex to pick out particular voices is done by two separate regions. They’re what allows you to sort and intensify particular voices in loud situations.

  • Superior temporal gyrus (STG): Sooner or later your brain will need to make some value based decisions and this happens in the STG after it receives the voices that were previously separated by the HG. Which voices can be freely moved to the background and which ones you want to pay attention to is figured out by the STG..
  • Heschl’s gyrus (HG): The first sorting phase is managed by this part of the auditory cortex. Researchers found that the Heschl’s gyrus (we’re simply going to call it HG from now on) was processing each distinct voice, classifying them into individual identities.

When you have hearing impairment, your ears are lacking particular wavelengths so it’s harder for your brain to recognize voices (high or low, depending on your hearing loss). Your brain can’t assign individual identities to each voice because it doesn’t have enough data. It all blends together as a consequence (which means discussions will more difficult to follow).

New Science = New Algorithm

It’s typical for hearing aids to have functions that make it easier to hear in a crowded situation. But now that we know what the fundamental process looks like, hearing aid manufacturers can incorporate more of those natural operations into their device algorithms. For instance, you will have a better capacity to hear and understand what your coworkers are talking about with hearing aids that help the Heshl’s gyrus and do a little more to differentiate voices.

Technology will get better at mimicking what occurs in nature as we learn more about how the brain functions in conjunction with the ears. And that can lead to better hearing outcomes. That way, you can concentrate a little less on straining to hear and a little more on enjoying yourself.

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